The Impact of Contralateral Cooling on Skin Capillary Blood Cell Velocity in Patients with Diabetes mellitus

In healthy volunteers, cooling of the contralateral hand leads to a rapid decrease in the ipsilateral capillary perfusion via a nerval reflex arc. The aim of this study was to investigate whether this reflex arc after contralateral cooling might be altered in patients with diabetes mellitus with and without peripheral neuropathy. Therefore, 12 patients with diabetic neuropathy (4 IDDM, diabetes duration 17.2 ± 2.9 (SD) years, age 60.8 ± 4.0 years, HbA 1c 6.5 ± 0.3%) and 12 patients with diabetes mellitus but without neuropathy (6 IDDM, diabetes duration 15.1 ± 2.7 years, age 55.9 ± 4.5 years, HbA 1c 5.4 ± 0.1%) were investigated by nailfold capillaroscopy. Twelve healthy volunteers (age 56.8 ± 3.1 years, HbA 1c 4.8 ± 0.2%) served as controls. Contralateral skin capillary blood cell velocity was determined at rest and during the following 20 min after cooling of the hand (3 min at 15°C). Blood pressure, heart rate and local skin temperature were examined regularly during the investigation. Resting capillary blood cell velocity did not differ between patients and controls. While contralateral cooling resulted in a decrease in capillary blood cell velocity (CBV) in controls (0.29 ± 0.05 vs. 0.42 ± 0.05 mm/s, p < 0.03), CBV remained unchanged or was delayed in patients. These results demonstrate that in diabetic patients nerval reflex arcs are impaired. A long-term follow-up in a larger number of patients is required to evaluate whether these findings might serve as a very early diagnostic tool for the diagnosis of developing diabetic neuropathy.